2.5L Pico Reef Concept (Lots of 3D Printing)

[Polymate3D]

Pump Update

So I have started work on the Micro controller side. This is starting with the pump, as the heater and lighting side can be done relatively easily, but the temperature detection and pump control will be more of a challenge. I am waiting on some thermistors, so thought I would start on the pump.

The current pump is 3.2 ohm and the target transistor has a current capability of 800mA. The voltage powering the entire project is 5V DC.

5V = I * 3.2ohm
I = 1.56A = 1,560mA

This is way too much. The end solution will be changing the pump to 6.4 ohm or 8 ohm. I have this one at hand however, and I also have some power resistors, so I added a 3.9 ohm power resistor in series for the time being.

This mean once the pump is modified to run without the resistor, it may be a little bit more powerful than it currently is, but I believe it has enough power regardless for the tiny 2.5L, 0.6G Pico reef.



So hopefully you can see from the video posted above that it is successfully doing both modes. Originally it had a lot of popping noise, but some filter capacitors have resolved this.

As I continue to develop the micro controller side and its functions, I will be sure to keep updating here. Away from this aspect of the project I will be attempting to gather some more accurate measurements of the container to allow me to design as tight a design lid as possible.

- Paul

 

[Polymate3D]

Heating Element

Sticking to the theme of the project, the heating element is custom made:

A 3D printed ring is made with enamelled wire used to create a set resistance. This windings surface area and resistance is made so that the maximum temperature is in a safe running region. In this original one it is around 55c. This is subject to change however.

This 1st iteration was 2.5W, but after 24 hours only managed around a 3 to 4c increase over ambient. The plan from here is to run 2x 3W elements. 1 slightly larger than the other.

These elements sit directly underneath the container, with a thermistor contacted to the container. This contact will likely be done on the back side of the container, but this will be tested in various places.

There is a few reasons for this, but the key one for now is this keeps the actual aquarium as clear from electronics as possible, keeping the limited space open to the animals going in it, and no other things detracting.

The circuit side is looking to get around to a accuracy of 0.12c, so we will be able to get fairly accurate and consistent readings. On top of this, we have 2 heating elements, meaning we can have:

Off
Low
High

Modes. The aim is the micro controller will regulate this temperature. In testing I will be capturing this data onto a SD card to help come up with the test temperature regulation control. The hope is to create a setup which learns how much to keep the heating elements on once the temperature is reached.

The micro controller will also be able to turn on and off a fan built into the lid, meaning it will regulate temperature both up and down. Something I feel is key for a Pico reef.

Still lots more to do, but its shaping up.

- Paul

 

[Polymate3D]

Pico Lid Design

So been a while since a update. As I said before, its not my core focus but a side one with many aspects to work on. Here is a look at how the lid is shaping up

The lid is broken up into 4 modules and a cross section centre section. The entire thing can be pulled off the top easily for easy access.

The 4 modules can fit into any of the 4 sections. By filling all 4 sections, the lid is sealed. These modules currently are:

1 = Pump
2 = Gravity Auto Top Top bottle
3 = Feeding / Water change access
4 = Fan cooling

The centre section will house the LED lighting. This lighting is currently targeting a 120 degree spread to enable the LEDs to mix well.

The layout and LED strength is subject to change, but the initial plan is a 1W LED in the centre, and 4 0.07W LEDs around this central one, totalling 1.28W of lighting on a 2.5L (0.7G) Pico Reef.

1W initially will be a 440nm Royal Blue LED, making up 78% of the entire power output. Then there will be 2 395nm LED's and 2 Cool Whites. The idea behind the light was to get what I need and make it as cost effective and as small as possible. I have plenty of other LEDs and can go much higher in output if needed.

The target for corals BTW is softies and maybe 1 or 2 LPS. No SPS.

Because I will be using a micro controller, these LEDs will not be set to ramp up / down, but will come on in stages.

Speaking of the micro controller, the code for it is currently around 200 lines long, but still needs various bits added to it to achieve all the plans. Off course once the code is done it will need to be run and revised until all issues are ironed out.

I may also attempt to design and get my own PCB's made for a cleaner look, so yet another thing to dive into!

I am now at the stage of starting to 3D print some of these pieces and see how they come together. The next update will likely be in the new year and will cover some changes to the pump. Don't worry, its all good!

See you in the next post, and as always, any questions / concerns, don't hesitate to mention them. - Paul

 

[Polymate3D]

Hands on with LEDs

So pretty happy with how things are shaping up with the lighting. Funds are very tight, but hoping to obtain a Seneye or find somewhere to rent a PAR meter at some stage. If I do get my hands on one, I will show some of the data.

This 1st image shows where the LEDs will be housed. The central LED is currently a 440nm LED to act as the main photosynthesis.

Other weaker LED's are 395nm here and 2 cool whites. It looks a little too blue initially to me, but I tend to lean towards white aquariums normally, and this is pushing away from that. Here is a slightly better view from the front.

In real life it does looks more white than this and with more of purple tint to it. The good news is the lid can take 5 different LED's and my circuitry can take 5x 1W LEDs if needed, but will likely be overkill. All LEDs being used currently have a 120 degree spread and the leakage out of the acrylic container is fairly minimal which is also good.

Working on the new pump and need to adjust the base for the heating elements. Got a long way to go such as PCB design, but 1st iterations will be done on breadboard and with some extra features.

Getting exciting though. All the parts needed to get the ball rolling are coming together!

- Paul

 

[Polymate3D]

Seneye Data

So I got myself a 2nd hand Seneye reef and have started using it to get some ballpark figures to see how the light is currently stacking up for my plans.

PUR was 84<86% with the 440nm LED which is the primary

66 PAR at the bottom
128 PAR at the middle
240 PAR at the top 2<3cm of water

The target is softies and some LPS so I think that hits the target nicely. There will be some lower powered 395nm LEDs to help extend down a bit and then low powered cool whites to make the aquarium not look super blue.

The way the LEDs mount is not to my liking, so I will be changing that and then taking measurements again.

Main thing is the light coverage in spectrum is good. The LEDs are 120 degrees and so coverage across just 15 x 15cm is naturally fine. The strength is also looking good.

Next step is designing the new upgraded pump into one of the modules, along with the heating elements and get some more parts 3D printed!

- Paul

 

[Polymate3D]

Pump Revisions and Project Changes

Hello. This is still in the design phase, but a few decisions have been made which have altered some plans, but lets start with a image and the pump revisions

Pump V2

This new pump runs one of my larger 3D printed loudspeaker drivers which also have a more powerful motor. This should increase the abilities of the pump. Unlike the 1st one, the driver is heavily revised to work better as a pump than a loudspeaker.

This pump utilises the piston function of the pump on both sides. The one facing down continues to use a chamber that's in contact with the water to create flow, standing waves or a mix. This driver has a large surface area and throw, allowing it with the extra power it has to shift more water.

On the other side, it now will have 2 one way valves and a pipe system. This will suck in air and then pump it into the area above the water surface. The lid will be creating a very good seal, and so this will allow a small by regulated airflow into the aquarium. All aimed at reducing evaporation.

Which leads nicely into the project changes section!

Project changes

(1) Gravity fed auto top up and fan cooling to be dropped

Doing some more research and talking to more people, it would seem evaporation is still a key concern, but in the aim of making this pico as easy and as stable as possible, I have opted to look down the Peltier and fan route to cool the aquarium in hot weather over the fan and fresh RO method.

1st reason is no RO top up needed. Uses a bit more power but the aquarium is 2.5L...so it should be too much.

2nd reason is I can regulate the cooling rate more easily with this than a fan evaporating the water.

3rd reason is that is would be a simpler system once in place. Forget RO water? no problem!

(2) Modular lid design removed

With the auto top up removed, there is less need for the modular compartments, as 2 have been removed. Macro algae was another but this could be integrated into the aquascape or a separate compartment.

By removing the modular aspect, I have create a lid with a tighter sealing design and reduce complexity.

How will the cooling be fitted?

The current plan is to have a tight sealing base with will contain the Peltier cooling side, along with the 2 heating modules. These will then be in a pocket of air which is trapped below the aquarium, leaving the may route for the heat or cooling to be transferred is through the base of the aquarium.

By using a thermistor elsewhere and comparing the time delay, or even another thermistor within the pocket of air, I should be able to create some code to more closely regulate the temperature of the aquarium. The key thing here is that we have more control over the heating and cooling of the internal volume already contained with the aquarium to keep values as stable as possible.



So that is the update for now. I am still designing the new lid and will likely need a few revisions, but the result should be better all round and with reduced material / 3D print times as well.

As always, feel free to tell me your opinion and ask questions!

- Paul

 

[Weller]

Micro controller wise I will be going with Arduino as it is what I know. Maybe after the setup is done and works I will venture into something like a Raspberry Pi Pico and get it online as well

Potentially consider using an esp32, they can be programmed in arduino ide, are powerful enough to use a camera (still images) they are already WiFi/ble enabled and are just about as cheap. If you went down the path of designing a pcb you could include alot of feature's.

 

[Polymate3D]

Potentially consider using an esp32, they can be programmed in arduino ide, are powerful enough to use a camera (still images) they are already WiFi/ble enabled and are just about as cheap. If you went down the path of designing a pcb you could include alot of feature's.

I will consider it for a larger and complex version if I am happy with my initial goals. The plan for this build is to run off a custom PCB and a ATtiny13, so very small and low cost, which makes sense for this application.

For more advanced stuff I am also considering the Raspberry Pi Pico with wifi. More to learn but the ability to expand would be vast.

Currently my main aquarium is causing me all manner of problems and so this concept is on the back burner, with a absolutely tiny 0.7L one being used to test the circuit board and ideas. Already need to get a new PCB done but can still learn some more before that one.

Thanks for the input! It may end up becoming a bigger focus if development goes well.

- Paul

 

[Polymate3D]

Minor Update

I am using my even smaller 0.6L micro reef container for quicker testing of ideas, especially around the lid and base designs.

My 2nd PCB design is done and now awaiting to be made. Target heating power is to be around 7W maximum. Previously I was winding enamelled wire but decided this is a tedious and likely not required at such a small heat load.

Therefore this PCB has 8 power resistors which are being used in 2 pairs of 4. This will allow it to switch between the 2 pairs to reduce maximum temperature.

Each resistor under the worst scenario will be generating 0.88W of heat, which translated from datasheets would be a maximum temperature rise of 49c over ambient, or around 74c maximum which is way within the specification of the board components.

The ATtiny13 IC has a internal temperature sensor and will be in the base with these resistors, so I will look at trying to use this as a safety mechanism if high air temperatures are occurring. Under normal conditions the heating amount will be fairly minimal, and so the temperature in the base chamber will be around the aquariums 25c target.

Pump is reduced to 8 Ohm which on a 50% duty cycle should be around 1.5W power draw which again is outside the aquarium itself. I am gluing parts of the pump together now to run flow tests and confirm if this is enough or not.

The LED is being controlled now by a manual switch on the back of the base, but the circuit has also been made so this could be swapped out for a USB timer plug as well, as I know this is something many people would want.

Serial output has been added so I can get the IC to print out raw data during testing so I can see what is going on and improve temperature regulation.

Cooling is also on this board to run a fan or a low power TEC. I have both here to test with, so hopefully this board will cover this aspect as well.

The board has also been changed from a square to a thin and long board to put all block terminals to face the back of the aquarium base.

Hopefully the next one I can talk about how the pump and flow is going. I expect it to be a few weeks before I have this board and components soldered down ready to go.

- Paul

 

[Polymate3D]

3D Printed Piston Pump Update

So generation 2 of the piston pump concept has been created. This new one runs at 8 Ohm, has a larger diameter voice coil for heat dissipation and a stronger motor this time around. Size wise it is a bit smaller as this version is on the baby 0.6L 10cm cube concept tank. This just makes print times and testing quicker.

The flow rate now is vastly improved and at a lower power consumption as well. For the 2.5L aquarium I will simply design a larger piston design so it is displacing as much a difference as this one is here.

The motor is still houses in the lid away from the water, so not adding to the heat input to the aquarium. This video also shows the planned light now. More white than early on to give soft corals a better looks, which is the key focus here. Softies and LPS.

Mainly going to be waiting on the new PCB's now. Whilst waiting I will revise the base to accomodate the new board. Then we can move on to heating the aquarium and confirming temperatures achievable and power draw.

- Paul

 

[Polymate3D]

Minor Update

The 0.6/0.7L test aquarium with the new board and heating modules was able to produce a maximum temperature increase over ambient of +8c. In this case, the room was 23c and the aquarium reached 31c. This bodes well for the 2.5L as well, as the cover was very thin and the base had screws coming out which was sinking heat out from underneath.

The resistor heating method however is rather delayed to heat and cool, and the surface temperature is not ideal, so I will be reverting to copper coils. This method on a large PCB or SMD resistors on a aluminium bed would be helpful, but I will be opting for the coil method.

Lighting works well on this board as well, but it isn't without its issues. The power delivery directly into the IC causes it sometimes to hang on power on, and the pump circuit was not wired correctly to as as a high pass filter in my circuit. Both issues however are easily resolved.

I will continue testing with this board whilst designing another. I am also looking into a DC motor based pump to simplify the pump for now, giving me time later on to perfect this aspect.


- Paul

 

[Polymate3D]

DC Pump Concept

So couple of updates to come, but will leave the other until I finalise it. Today is the DC pump concept.

This 3D printed pump uses a small DC motor which is housed in the aquarium lid. The impeller design extends into the inlet pipe and should be submerged. The section above the impeller indents in > < to prevent water splashing or forcing its way up to the motor which is out of the water. There will also be a cover with a opening just about big enough for the motor shaft.

The impeller itself is designed with curved blades which acts to pull the water up from the inlet, and the base of the impeller blades have a smooth curve to make the transition of flow from upwards to sidewards as clean as possible.

As you can see from the short video, the impeller is very effective. This is at 1W which is great for this use case, and being controlled by the micro controller, we can adjust duty cycles to change the speed at which it works.

The housing is a simple inlet with the impeller reaching in, followed by a angled in and down outlet. This is to prevent splashing upwards and get down to the aquarium base.

The bottom of the housing has a 3D printed thread. This is there to allow me to attach a filter section. This will also make it easy to remove if successful.

The DC motor itself will be held in the aquarium lid, with a separate piece made to fit the DC motor. This along with the impellers deeper body and implementation to stop water from rising is hoped to remove any chance of contact with the metal shaft or the motor itself.

If this is the pump choice in the end, naturally this will be tested and checked.

I will post back when I have progressed further. Until then, any questions or ideas, feel free to post a reply and I will get back to you!

- Paul

 

[Polymate3D]

DC Pump Testing

So initial build is up and running. Some tolerance things I would change, but overall a very good 1st attempt when it comes to assembly.

Here is a short video of it running at it's full 1W power mode (5V @ 200mA):


This as you can see if way overkill for these small aquariums. A quick test in my Fluval Flex 34L Quarantine aquarium showed that it faired pretty well even in that! so I worked on dialling down the power and found this as a ideal power output for this little 0.7L aquarium:


I did this by adding power resistors until I found a nice flow. I then grabbed the old multimeter to measure voltage and current, which was 1.6V and 63mA

1.6V * 0.063A = 0.1008W

or basically 0.1W of power. Super tiny power draw and highly efficient!

I was not confident in this and so hooked up the motor to a single AA battery and performance was only slightly down at 1.4V and 52mA (0.07W), so it is indeed delivering the performance needed at much lower than expected levels. It makes me excited for the possible flow methods this could produce when paired with the micro controller!

Now things I would change is to design the impeller to be deeper, as it creates some noise due to air bubbles. I would also look at increasing the tolerance gap around the impeller to reduce potential noise and bubbles stuck inside. This would reduce performance, but looking at how this is performing, I am not that concerned currently.

Next update should hopefully be testing a new heating module, or discussing the light which is also fitted into the aquarium lid.

- Paul

 

[Polymate3D]

Revised DC Pump - Is this still too much flow?


Please watch and give me your verdict. My feeling is that even at this slower pace it is still too much and so slowing it down even more will need to be done. The plan is soft corals and LPS. This is 10% of its potential.

The revision simply lowers the pump and gives a bit more of a gap between the impeller and it's housing.

Thanks for any feedback given in advance. Next update should be a new PCB design, permitting I designed it right....stay tuned!!!

- Paul

 

[Polymate3D]

Test Run on new PCB

So since last post I have got a new PCB design in. It again has some issues but it much better then my originals and now includes heatsinks to help transfer the heat from the base of the aquarium to the aquarium itself. They do not make contact, but simple help to get the trapped air below to the desired temperature.

I have also hooked up the little LED I am using, and set the DC pump to a simple pulse every second for now to tame how powerful it can be.

So check it out. A baby 0.7L (0.2 US gallon) aquarium!


The 1st test is confirming how much it can heat the aquarium up beyond ambient, and then work on the thermistor circuit will start. I already have some code setup to try which will try and learn how much power in heating or cooling will be needed on a hour by hour basis, but I will be testing these functions on just plain water. No saltwater or livestock.

Cooling will have to be just a fan on this PCB, but I have already learnt my mistakes and a new PCB will be designed and made for the project as a whole. This one however may be enough for this little 0.7L aquarium at least, Possibly even enough for the 2.5L testing.

I shall post again once I have temperature data, but for now, just enjoy the colour and the water rippling it is already creating

- Paul

 

[Polymate3D]

Heating Test

So I ran a 3 hour test on maximum power (Around 4.6W). The ambient temperature here is currently too high at 26c(79f), so just measuring how much it can rise above ambient temperature.

30 Minutes = +2.1c
65 Minutes = +3.9c
95 Minutes = + 5.1c
120 Minutes = +6.0c
180 Minutes = +7.3c

The result was 33.3c which is a 7.3c rise over ambient. This means it should be okay in rooms as low as 17c(63f).

I then turned it off completely and the drop off naturally from such a small volume of water was also very quick.

30 Minutes = -1.0c
75 Minutes = -2.6c
90 Minutes = -3.1c
135 Minutes = -4.1c
195 Minutes = -5.0c (28.3c)

So once you get around 2<3c above ambient the roll off is slow enough and easy enough to tackle. Does however show the importance of temperature control on Pico aquariums. This is a Acrylic aquarium as well with a lid on top. Glass with a open top would be even worse. Placed the data here for anyone in the future who may find this useful for there own Pico Aquariums.

As stated in the previous post, the code is not a simple , if below 24c turn on, if above 25c turn off setup. Once it gets within a window, it tracks how much often it is heating (and in the next revision, cooling) so it can learn a average, and then alter throughout the day to try and stay stable within this window.

I have now set the code to see how it fairs, but the temperature is too high, so may have to find a alternative to allow me to test it.



I think after being the only poster on this thread for the last 8 posts in a row, I will leave the updates on development and do that behind the scenes, then post when I am actually setting it up with something alive.

Hope the data is helpful

- Paul